The present invention relates to improvements in an apparatus for measuring the cohesion force of particulate materials.
Various apparatus are known for measuring the cohesion force of particulate materials. They include an apparatus comprising a bottomed container composed of a fixed container segment and a movable container segment separable from each other for containing the particulate material as compactly placed therein, a drive assembly for moving the movable container segment in a direction approximately perpendicular to the plane of separation of the container to divide the particulate material in the container into two, and an external force detecting unit for detecting the external force to be applied to the movable container segment by the drive assembly. With this apparatus, the container segments are pulled away from each other by the drive assembly, with the bottomed container filled with a specimen of particulate material as compacted therein, and at this time, the external force detecting unit measures the tensile strength of the particulate material. The cohesion force of the material is determined based on the measurement. The invention relates to improvements in the apparatus of this type.
FIG. 8 shows such an apparatus heretofore available. The apparatus includes a bottomed container 5' comprising a fixed container segment 5a' and a movable container segment 5b' which is movably supported on ball bearings 33. Since the ball bearings 33 are thus used, the conventional apparatus requires extremely high precision in machining the rolling surface or groove for the bearings 33. Moreover, even if fabricated with high precision, the apparatus has another drawback that the ball bearings 33 involve unnegligible rolling friction which impairs the accuracy of measurements despite the resulting increase in the overall cost of the apparatus. The apparatus has still another drawback. When the container 5' is filled with a specimen of particulate material, S, the specimen must be compacted under a load, but there is a limitation on the load applicable to the specimen S in view of the strength of the rolling surface for the ball bearings 33. This in turn imposes limitations on the measuring condition and, accordingly, on the usefulness of the apparatus.